Rotary fluid seal



Dec. 15, 1953 2,662,785

T. L. FAWICK ROTARY FLUID SEAL Filed July 8, 1950 2 Sheets-Sheet 1 FIG. I

FIG.5

INVENTOR.

THOMAS L. FAWICK ATTORNEY Dec- 5, 1 Y T. L. FAwlcK 2,662,785

ROTARY FLUID SEAL.

Filed July 8, 1950 1 2 Sheets-Sheet 2 mmvroxQ THOMAS L. FAWICK ATTORNEY Patented Dec. 15, 1953 ROTARY FLUID SEAL Thomas. L. Fawick, Cleveland, Ohio, assignor, by

mesne assignments, to. Federal. Fawick Corporation, a corporation of Michigan.

Application July 8', 1950, Serial No. 172,687

3' Claims.

This invention relates to a rotary seal, for maintaining sealed communication between a fluid passage or a plurality of fluid passages in a member and a fluid passage or respective fluid passages in another member while one of the members rotates in relation to the other.

The example chosen for illustration in the accompanying drawings is adapted for use in an excavator of the shovel, clam-shell or other type. In such an assembly the rotaryseal is provided to enable the operator in the cab to supply compressed air, from a source of supply on the cabassembly, selectively to a plurality of fluid actuated devices, such as clutches and brakes, mounted upon the chassis frame, while permitting the cab frame to turn, in accordance with the usual practice, upon the chassis frame.

My chief objects are compactness, simplicity, durability, dependability, and economy and facili ty of assembly; disassembly and repair.

Further objects are to provide, in a multiplepassage rotary seal, a high degree of symmetry of parts and elements; to provide uniformity of sealing pressure per unit of length of slip-seal members sealing the several passages, even though the said members be of different lengths, as in the case of a plurality of concentric rings defining a plurality of concentric annular flow passages; to provide an improved seal adapted to function with regard to fluid flowing in either direction through it, as in the case of both charging and venting fluid actuated devices through the seal; and to provide these advantages permissibly' without the use of springs.

Of the accompanying drawings;

Fig. 1 is a vertical middle section of a seal embodying my invention in its preferred form for a four-passage seal, with a diagrammatic showing of adjacent parts of an excavator in which the. seal is incorporated.

Fig: 2- is/a top view of parts shown in- Fig. 1.

Fig. 3.15:8, section on line 3--3 of Fig. 1'.

Fig. 4 is a section on line 4-4. of Fig. 1,.

Fig. 5 is. a fragmentary section showing a desirable form of gasket ring and grooves in which it is mounted.

Referring to the drawings, ill is the chassis frame of an excavator and II is the cab frame rotatably mounted thereon in the usual manner, with the usual gearing and, supporting rollers, not shown, interposed between the two.

A largeking-pin I2, permissibly rigid with the chassis frame Ii], centers the cab frame I! and is centrally formed with a vertical through bore I3' through which loosely extends a fluid conducting structure comprising pipes I, 2, 3 and 4 equally spaced about a common center and pressfitted at their upper ends in respective holes la to la in a casting I4, and at their lower ends in respective holes such as the holes 31), 4b in a casting I5. Theupper casting M has a stem which is: press-fitted in and welded at It to the upper end of a tube I1 and the lower casting I5 has a stem press-fitted in the lower end of the tube IT. At the lower end of this fluidconducting structure the fluid passages I, 2, 3' and 4 are provided with suitable connections, such as those shown for passages 3 and 4 at 30 and do, for conducting fluid selectively to and from fluidactuated devices not shown.

Between the cup-shaped casting I 4 and the upper end face of the kingpin I2 is mounted a thrust-bearing ring I8 which is held against rotztion with relation to the king-pin I2 by dowels Upwardly" the casting I4 is of cup-shape and by reason: of suitable plugged cross-bores in the casting, as shown, the fluid passages In to la. in the structure above described are in communication respectively with a central, fluid-receiving bore Id in the floor face of the cup-shaped portion of the casting I4 and concentric, arcuate, fluid-receiving slots 2d, 3d,, and 4d extending upwardly from the. respective plugged bores to the flooriiace, of the cup-shaped portion of the castmg This floor face..- of: the cupeshapcd portion of the casting I4. is formed with concentric grooves in which are mounted respective sealing rings Ie to 49, preferably of oil resistant synthetic rubber, the upper parts of which occupy corresponding grooves formed in the lower faces of a set of annular slip-seal members if to M, of carbon or other suitable slip-seal, material.

These. slip-seal rings If to 4 have their upper edge faces finished for slip-seal coaction with a plane-faced sealing member 22, having a hardened and ground lower" face, which is accurately held, rotatably, in the cup-shaped part of the casting I4, with the. deformable rings if to 4 under substantial compression, by radial-andthrust bearing. balls 2|, 2| interposed between a raceway shoulder with which the, member 26) is formed and a hold-down ring 22 which fits within a centering flange 23, on the casting I4, the holddown, ring, 22 being secured upon the casting I4 by screws 2.4, 2.4. An oil retaining and dust excluding packing 25 is provided between the members 20 and 22.

The set of deformable rings Ie toie: andv the slip-seal members if to 4]" by which they are embraced, define a central flow chamber 59 and concentric annular flow chambers 2g to 49 surrounding it, these four flow chambers being in communication respectively with the flow passages I a to to in the above described structure, and thus with the pipes l to l extending downwardly through the hing-pin E2.

The arcuate slots to id, through which the annular flow chambers 2g to "to have such communication, are of such length as to provide adequate 'iow capacity even though the slots are narow radially for providing an assembly or" small diameter.

The central flow chamber to is in communication an through bore iii in the member 20 and win charging-and venting pipe or hose ii coupled thereto, and, through arouate slots 29' to 4;? in the lower face of the member 23, the flow chomb s to to to are communication respectively with charging and venting pipes or hoses 22' to it.

In the operation or" the seal, selectively are connected at will, by manipulation of respective manually controlled valves (not shown), with a source of pressure fluid on the cab frame H and, on occasion, with the atmosphere.

Even though the cab frame ii be rotated in relation to the chassis is, fluid pressure in each of the flow passages i to will be controlled in accordance with the fluid pressure in the corresponding one of the pipes ii to 42'.

Preferably each of he slip-seal rings if to A) is formed. with annular shoulders as shown so that sealing face against the member so will be desirably narrow, to assure a proper amount of sealing pessure per unit of its area contacting the member 21 The shape and proportions of the deformable sealing ring to to ie and adjacent parts are such that the rings are put under substantial compression in the assembling of the parts to provide, by their recoil, adequate sealing pressure between them and the members that they contact and between the siip-seal rings if to M and the finished lower face oi the member 2%), even though suction be ap lied to one or more of the annular chambers to to or different pressures concurrently appli d to different ones of those chambers.

To provide adequate scaling pressures and ye have the rings to to do fit their preferably on"- cular-secticn grooves when the rings are compressed, each ring may given a somewhat elliptical cross-sectional form, with the long axis vertical, as shown clearly in 5.

The grooves preferably are of circular sect on so that the rings are well held against being wedged by fluid pressure into the space between plane adjacent faces of the members all and M, as occ r when the deformable ring is opposed by a pair of rectilinear faces that are pronouncedly oblique all of the way to the aciacent faces of the members I? and. 2E. All of the slip-seal rings if to of are of suc cross-sectional shape and size that effective d1- rect fluid pressures upon them are substantially balanced as to any effect upon their sealing pressures.

Preferably the slip-seal faces of the if to 4 are all of the same radial width, all of the deformable rings is to be are given the sa .e percentage of vertical compression and each slip-seal ring If to 4 has the same medial circular length as its associated deformable ring. Then the slip-seal pressure per unit area will be the same at all parts of the slip-seal areas because the compressed deformable rings, although of successively greater circumferential lengths, will be exerting their pressures against slip-seal surfaces of proportionate lengths and consequently proportionate areas.

The arrangement as describec is such that the set of deformable rings, Ic to do, sealed in their grooves in both the member and the respective slip-seal rings If to M, serve to lzeep the latter in proper concentric relation.

The deformable rings is to ie, by reason of the frictional grip of the members embracing them, prevent the slip-seal rings 51 to if from turning in relation to the member i l.

In the assembling of the parts the deiormable rings is to 4e are simply laid in their respective grooves in the floor surface of the member :4, after which the slip-seal rings if to G are simply set upon their respective deformable rings, automatic centering or" all of the rings thus being provided. Ehen the mounting of the member 22, balls 2! and hold-down ring is easily performed. Disassembly also is easily performed by a reversal of the described operations.

A single plane face of the member 23 requires to be lapped to provide its several annular slipseal areas. The slip-seal rings If to 4) are individually formed to the same height of siipseal face but the resilience of the deformable rings le to la provides a substantial tolerance in the matter of accuracy of original dimensions and of dimensions after wear. The wear, however, is substantially uniform on all of the slipseal surfaces, because of the above mentioned uniformity of the sealing pressure per unit of area of slip-seal surfaces.

Because of the circular-arc shape of the grooves in the members that embrace the deformable sealing rings the latter can have some self-energizing efiect, under the force of diiierential fluid pressure, in addition to their initial compression, in sealing against the walls of the grooves, and in providing slip-seal pressure, whether the greater fluid pressure is against the inner periphery or against the outer periphery of the ring.

Modifications are possible within the scope of the invention as defined by the appended claims.

1. A rotary seal comprising two relatively rotatable members each formed with a fluid passage and means for maintaining sealed communication between the two passages, said means comprising a substantially rigid slip-seal ring having slipseal face-to-face contact with one of the said members, on a'slip-seal face transverse to the axis of rotation, in a single annular slip-seal zone surrounding the passage of that member at a substantial distance from said passage and having slip-seal contact with only that member, said slip-seal ring being formed with an annular groove in its face farthest axially from that memher, the other one of said members having an annular groove surrounding its passage and facing the first said groove, and a static-seal ring of resiliently deformable material mounted under compression with a part of it in each of the pair of grooves and, by reason of its engagement with the walls of the grooves, constituting the only means for maintaining the centering and preventing rotation of itself and the slip-seal ring in relation to the one of the said members that does not have the recited slip-seal face.

2. A rotary seal as defined in claim 1 in which the recited grooves are of at least approximately circular-arc cross-sectional form and in which the deformable sealing ring, when in unstrained condition, is of approximately circular cross-sectional form but is of slightly greater dimension axially of the assembly than radially of the assembly, the assembly including bearing means for holding the two first recited members so spaced that the sealing ring is deformed to at least approximately circular cross-sectional form by being axially compressed by the walls of the grooves in which it is seated.

3. A rotary seal comprising two relatively rotatable members each formed with a plurality of fluid passages and means for maintaining sealed communication between fluid passages of one of the members with respective fluid passages of the other of said members, said means comprising a plurality of separate-individual, relatively movable, substantially rigid slip-seal rings having slip-seal face-to-face contact with one of the members, on slip-seal face areas transverse to the axis of rotation, each slip-seal ring being formed with an annular groove in its face farthest axially from the one of the said members with which it has slip-seal relation, the other of said members having an annular groove facing each of the said grooves, and a deformable static-seal ring mounted in each of the pairs of grooves, each slip-seal ring, as a ring, surrounding and maintaining sealed communication, through flow chambers, between a pair of the defined fluid passages in the said two relatively rotatable members, slip-seal rings of the set thus keeping each of the said flow chambers out of communication with the next, and at least one pair of the fluid passages in the said relatively rotatable members being in communication only through one of the said flow chambers between and defined by two of the slip-seal rings, the said static-seal rings, by reason of their engagement with the walls of their respective pairs of grooves, constituting at least the primary means for maintaining the said separate, individual slip-seal rings in centered relation and holding them against rotation in relation to the grooved one of the said relatively rotatable members.

THOMAS L. FAWICK.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 872,358 Liddell Dec. 3, 1907 986,439 Camp Mar. 14, 1911 1,948,963 Dukes Feb.' 27, 1934 2,200,151 Burkhardt May 7, 1940 2,404,494 Halby et a1. July 23, 1946 FOREIGN PATENTS Number Country Date 431,059 France Aug. 31, 1911 OTHER REFERENCES American Machinist, August 2, 1945, pp. 122- 123; Sealing Point Free of Flash Eliminate Packing Ring Leakage, by Harry G. Wessel, Westinghouse Airbrake Co. 

